Gastric Cancer Precursor Lesions (GCPL) Study

Background: Gastric cancer is a leading cause of cancer deaths around the world. This disease is a serious problem in places like East Asia, Central and South America, and Eastern Europe. Researchers want to study the causes of gastric cancer and its precursors. They want to reduce the number of people with stomach cancer. Objectives: To learn more about bacteria factors and other causes of gastric cancer. To study potential markers associated with precancerous gastric lesions (intestinal metaplasia). Eligibility: Adults ages 40-70 years at certain hospitals in Chile who: Are going to have upper gastrointestinal endoscopies OR have stomach cancer and need surgery Design: Participants will give gastric tissue samples. Some participants will donate a portion of the stomach tissue that is removed as part of their clinical care. Participants will give access to reports of their stomach exam. They will allow researchers to photograph the microscope slides of their tissue samples. Participants will answer questions. The topics of the questions include: Age, height, weight Education Habits including tobacco and alcohol Personal and family history of disease Reproductive history Diet Some participants will give blood, urine, saliva, and stool samples. Study staff will collect the blood. They will tell the participants how to collect the other samples themselves.